.esf File?

My company uses a dated estimation program written in java by a former employee who is no longer with us. The program is designed to pull actual labor rates and use them with actual machine times that are stored in files such as labor.esf, workstation.esf etc.

The idea is that in the UI of this program you can log in and change the labor values and overwrite the existing labor.esf file. The problem is, it's reverting back to the stored values when the program is closed. I googled .esf files to see if I could find an .esf reader or editor and found nothing even on the extension.

I'm obviously not familiar with java, but my only goal is to get the values updated so they better reflect our profit levels. Maybe the error in overwriting data is something you know how to troubleshoot. I'll provide any information I can, but again, I'm working with a very limited knowledge of java.

Not all file extension are know outside of your computer. I have several that I have created for my own use: NSS for Norm's Slide Show for example.
The use of your own extension is useful in that you can use the OS's file association table to control what program is executed when the file is double-clicked. For NSS my slide show program starts.

Past that I have no idea what your program does. If you don't have any documentation on the program, You should get a java programmer to look at the source.

Have you tried opening one of the files in wordpad to see if there is any text. If the file is mostly binary, then you will need a programmer.